1. Field of the Invention
The present invention relates to a RF signal detecting apparatus for liquid crystal display and a RF signal detecting method using the same, and more particularly to a RF signal detecting apparatus for liquid crystal display and a detecting method thereof, wherein a digitizer board for detecting a radio frequency signal (hereinafter referred to RF signal) emitted from a pen input device is integrated with a liquid crystal panel.
2. Description of the Related Art
Generally, a Tablet PC is a displaying and inputting device, comprises a liquid crystal panel module, a digitizer board, a digitizer control board and a pen tablet input device, and operates in such a manner that it emits a RF signal through a pen input device or a touch pad to a monitor and detects a location of the input device by detecting the emitted signal at the digitizer board.
FIG. 1A is a block diagram showing a RF signal detecting apparatus according to an embodiment of a prior art. As shown, the apparatus comprises a pen input device 10, a digitizer board 20 including a RF signal generator 20a, a RF signal transmitter 20b, a RF signal receiver 20c, and a RF signal detector 20d, a location calculator 30 and a system 40. Herein, the system 40 is a Tablet PC.
In the following, the operation of the RF signal detecting apparatus is briefly explained.
First, in the digitizer board 20, when the RF signal generator 20a emits a RF signal to the RF signal transmitter 20b, the RF signal transmitter 20b transmits the RF signal to the pen input device 10. The emitted RF signal is received into the pen input device 10, and then reflected and transmitted to the RF signal receiver 20c of the digitizer board 20.
Then, the RF signal detector 20d detects the RF signal received by the RF signal receiver 20c and transmits it to the location calculator 20c. Based on the RF signal detected by the RF signal detector 20d, the location calculator 30 calculates a horizontal (X) position and a vertical (Y) position when inputting by pen, transmits the resultant coordinate values to the system 40 via a serial interface.
FIG. 1B is a block diagram showing a RF signal detecting apparatus according to other embodiment of a prior art. In the figure, a pen input device is designated as a reference number 100, a RF signal generator is designated as a reference number 100a, a RF signal transmitter is designated as a reference number 100b, a digitizer board is designated as a reference number 120, a RF signal receiver is designated as a reference number 120a, a RF signal detector is designated as a reference number 120b, a location calculator is designated as a reference number 140, and a system is designated as a reference number 160.
Although the RF signal detecting apparatus of the FIG. 1B has a similar structure to that of the FIG. 1A, it has a difference in regard to generating a RF signal. Specifically, in the apparatus of FIG. 1A, the RF signal is generated by the RF signal generator 20a provided in the digitizer board 20 and emitted to the pen input device 10. However, in the apparatus of FIG. 1B, the RF signal is directly generated by the RF signal generator 100a provided in the pen input device 100 and emitted to the digitizer board 120. Except the structure difference, the operation of the apparatus of the FIG. 1B can be easily understood from the description of the FIG. 1A. Therefore, detailed explanations of it are omitted.
FIG. 2 illustrates a liquid crystal display equipped with a digitizer board according to a prior art.
As shown in FIG. 2, the prior liquid crystal display comprises a liquid crystal panel 200, a Source Printed Circuit Board 220 connected to a side of the liquid crystal panel 200 via a TCP (Tape Carrier Package) 210, a digitizer board 230 located to a back side of the liquid crystal panel 200 and detecting a RF signal, a digitizer control board 240 comprising a location calculator for calculating a horizontal (X) position and a vertical (Y) position when inputting by pen, and a system 250 receiving the calculated horizontal and vertical positions through the digitizer control board 240. A source driver IC 210a is mounted on the TCP 210 and a gate driver IC (not shown) is mounted on a TCP (not shown) connected to the other side of the liquid crystal panel 200.
As explained above, in the prior RF signal detecting apparatus, the digitizer board for detecting the RF signal is located to the back side of the liquid crystal panel. As a result, the position detection in pen inputting becomes inaccurate. The reason for this is that the RF receiver of the digitizer board cannot function properly due to the limitation of the frequency used in the liquid crystal panel.
Further, the prior RF signal detecting apparatus has many disadvantages such that the number of the parts and the manufacturing costs are increased when assembling.